uk.org.retep.util.classloader.DeploymentClassLoader Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of j2ee Show documentation
There is a newer version: 10.6
/*
 * Copyright (c) 1998-2007, Peter T Mount

 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 
 *   Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 *   Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 *
 *   Neither the name of the retep.org.uk nor the names of its contributors
 *   may be used to endorse or promote products derived from this software
 *   without specific prior written permission.
 *
 * 
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package uk.org.retep.util.classloader;

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import uk.org.retep.util.io.FileUtils;

/**
 * A class loader that will load a class from a set of child class loaders,
 * usually JarClassLoader instances.
 * @author peter
 */
public class DeploymentClassLoader
        extends CachingClassLoader
{

    private final Set loaders = new LinkedHashSet();

    public DeploymentClassLoader()
    {
        super();
    }

    public DeploymentClassLoader( final ClassLoader parent )
    {
        super( parent );
    }

    public DeploymentClassLoader( final File directory )
            throws IOException
    {
        init( directory );
    }

    public DeploymentClassLoader( final File directory, final ClassLoader parent )
            throws IOException
    {
        super( parent );
        init( directory );
    }

    private void init( final File directory )
            throws IOException
    {
        final List files = FileUtils.findFiles( directory,
                                                      FileUtils.JAR_FILTER,
                                                      false );

        for( File file : files )
        {
            add( new URLClassLoader( new URL[]
                                     {
                                         file.toURI().toURL()
                                     } ) );
        }
    }

    public boolean add( final ClassLoader loader )
    {
        return loaders.add( loader );
    }

    public boolean remove( final ClassLoader loader )
    {
        return loaders.remove( loader );
    }

    @Override
    protected synchronized Class loadClass( final String className,
                                               final boolean resolve )
            throws ClassNotFoundException
    {
        Class c = getClass( className );

        if( c == null )
        {
            final Iterator it = loaders.iterator();
            while( c == null && it.hasNext() )
            {
                try
                {
                    c = it.next().loadClass( className );
                }
                catch( ClassNotFoundException cnfe )
                {
                    // ignore, pass to the next class loader
                }
            }

            if( c == null )
            {
                throw new ClassNotFoundException(
                        "Unable to find class " + className );
            }

            putClass( className, c );
        }

        if( resolve )
        {
            resolveClass( c );
        }

        return c;
    }

    @Override
    protected URL findResource( final String name )
    {
        final Iterator it = loaders.iterator();
        while( it.hasNext() )
        {
            final URL url = it.next().getResource( name );
            if( url != null )
            {
                return null;
            }
        }
        return null;
    }

    @Override
    protected Enumeration findResources( final String name )
            throws IOException
    {
        throw new UnsupportedOperationException( "Not supported yet." );
    }
    
    
}